ECG assessment of IHD

ECG assessment of IHD

Presented by

Aser mohamed kamal

HISTORY1842- Italian scientist Carlo Matteucci realizes that electricity is associated with the heart beat1876- Irish scientist Marey analyzes the electric pattern of frogs heart 1895 - William Einthoven , credited for the invention of EKG1906 - using the string electrometer EKG, William Einthoven diagnoses some heart problems

CONTD1924 - the noble prize for physiology or medicine is given to William Einthoven for his work on EKG1938 -AHA and Cardiac society of great Britan defined and position of chest leads1942- Goldberger increased Wilsons Unipolar lead voltage by 50% and made Augmented leads2005- successful reduction in time of onset of chest pain and PTCA by wireless transmission of ECG on his PDA.

MODERN ECG INSTRUMENT

ECGAn electrocardiogram (EKG or ECG) is a test that checks for problems with the electrical activity of your heart. An EKG translates the heart's electrical activity into line tracings on paper. The spikes and dips in the line tracings are called waves. The heart is a muscular pump made up of four chambers .

Impulse Conduction & the ECGSinoatrial node

AV node

Bundle of His

Bundle Branches

Purkinje fibers

ECG Graph Paper

X- Axis time in secondsY- Axis Amplitude in mill volts

ECG Graph PaperX-Axis represents time - Scale X-Axis 1 mm = 0.04 sec Y-Axis represents voltage - Scale Y-Axis 1 mm = 0.1 mVOne big square on X-Axis = 0.2 sec (big box) Two big squares on Y-Axis = 1 milli volt (mV)Each small square is 0.04 sec (1 mm in size)Each big square on the ECG represents 5 small squares = 0.04 x 5 = 0.2 seconds 5 such big squares = 0.2 x 5 = 1sec = 25 mmOne second is 25 mm or 5 big squares One minute is 5 x 60 = 300 big squares

ECG Complex

P wavePR IntervalQRS complexST segmentT WaveQT IntervalRR Interval

ECG ComplexP Wave is Atrial contraction Normal 0.12 secPR interval is from the beginning of P wave to the beginning of QRS Normal up to 0.2 secQRS is Ventricular contraction Normal 0.08 secST segment Normal Isoelectic (electric silence)QT Interval From the beginning of QRS to the end of T wave Normal 0.40 secRR Interval One Cardiac cycle 0.80 sec

Identify the ECG Complex

Identify the ECG Complex

# of BoxesDuration The Wave or Interval (3) 0.12 secP wave : Atrial contraction (5)0.20 sec PR interval P to begin. of QRS (2)0.08 secQRS complex - Ventricular IsoelectricST segment - Electrical silence (3)0.12 secT wave - repolarization (2)0.08 secQRS interval Ventricular cont. (10) 0.40 sec QT interval - From Q to T end(5)0.20 secTP segment - Electrical silence

Let us Identify the waves

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Let us Identify the wavesP wave Atrial contraction = 0.12 sec (3 small boxes)PR Interval P + AV delay = 0.20 sec (5 small boxes)Q wave Septal = < 3 mm, < 0.04 sec (1 small box)R wave Ventricular contraction < 15 mmS wave complimentary to R < 15 mmST segment Isoelectric decides our fateT wave ventricular repolarization friend of STTP segment ventricular relaxation shortened in tachycardia

EKG Leadswhich measure the difference in electrical potential between two points1. Bipolar Leads: Two different points on the body 2. Unipolar Leads: One point on the body and a virtual reference point with zero electrical potential, located in the center of the heart

ECG Bipolar Limb Leads

+++---

RLFRFL

ECG Bipolar Limb LeadsStandard ECG is recorded in 12 leadsSix Limb leads L1, L2, L3, aVR, aVL, aVFSix Chest Leads V1 V2 V3 V4 V5 and V6L1, L2 and L3 are called bipolar leadsL1 between LA and RAL2 between LF and RAL3 between LF and LA

ECG Unipolar Limb Leads

+++Lead aVRLead aVLLead aVFRLF

ECG Unipolar Limb LeadsStandard ECG is recorded in 12 leadsSix Limb leads L1, L2, L3, aVR, aVL, aVFSix Chest Leads V1 V2 V3 V4 V5 and V6 aVR, aVL, aVF are called unipolar leadsaVR from Right Arm PositiveaVL from Left Arm PositiveaVF from Left Foot Positive

EKG LeadsThe standard EKG has 12 leads:3 Standard Limb Leads3 Augmented Limb Leads6 Precordial Leads

Standard Limb Leads

Standard Limb Leads

Augmented Limb Leads

All Limb Leads

Precordial Leads

Precordial Leads

ECG Chest Leads

ECG Chest Leads Precardial (chest) Lead Position V1 Fourth ICS, right sternal border V2 Fourth ICS, left sternal border V3 Equidistant between V2 and V4 V4 Fifth ICS, left Mid clavicular LineV5 Fifth ICS Left anterior axillary lineV6 Fifth ICS Left mid axillary line

Right Sided & Posterior Chest Leads

Arrangement of Leads on the EKG

Anatomic Groups(Septum)

Anatomic Groups(Anterior Wall)

Anatomic Groups(Lateral Wall)

Anatomic Groups(Inferior Wall)

ECG RULESProfessor Chamberlains 10 rules of normal:-

RULE 1 PR interval should be 120 to 200 milliseconds or 3 to 5 little squares

RULE 2The width of the QRS complex should not exceed 110 ms, less than 3 little squares

RULE 3The QRS complex should be dominantly upright in leads I and II

RULE 4QRS and T waves tend to have the same general direction in the limb leads

RULE 5All waves are negative in lead aVR

RULE 6The R wave must grow from V1 to at least V4The S wave must grow from V1 to at least V3 and disappear in V6

RULE 7The ST segment should start isoelectric except in V1 and V2 where it may be elevated

RULE 8The P waves should be upright in I, II, and V2 to V6

RULE 9There should be no Q wave or only a small q less than 0.04 seconds in width in I, II, V2 to V6

RULE 10The T wave must be upright in I, II, V2 to V6

Important PrecautionsCorrect Lead placement and good contactProper earth connection, avoid other gadgetsDeep inspiration record of L3, aVFCompare serial ECGs if available Relate the changes to Age, Sex, Clinical historyConsider the co-morbidities that may effect ECGMake a xerox copy of the record for future useInterpret systematically to avoid errors

Normal ECG

Normal ECGStandardization 10 mm (2 boxes) = 1 mVDouble and half standardization if requiredSinus Rhythm Each P followed by QRS, R-R constant P waves always examine for in L2, V1, L1QRS positive in L1, L2, L3, aVF and aVL. Neg in aVRQRS is < 0.08 narrow, Q in V5, V6 < 0.04, < 3 mmR wave progression from V1 to V6, QT interval < 0.4 Axis normal L1, L3, and aVF all will be positiveST Isoelectric, T waves , Normal T in aVR,V1, V2

Be aware of normal ECGNormal Resting ECG cannot exclude diseaseIschemia may be covert supply / demand equationChanges of MI take some time to develop in ECGMild Ventricular hypertrophy - not detectable in ECGSome of the ECG abnormalities are non specificSingle ECG cannot give progress Need serial ECGs ECG changes not always correlate with Angio resultsParoxysmal events will be missed in single ECG

Normal Variations in ECGMay have slight left axis due to rotation of heartMay have high voltage QRS simulating LVHMild slurring of QRS but duration < 0.09J point depression, early repolarizationT inversions in V2, V3 and V4 Juvenile T Similarly in women also T Low voltages in obese women and menNon cardiac causes of ECG changes may occur

P waveAlways positive in lead I and II Always negative in lead aVR < 3 small squares in duration< 2.5 small squares in amplitudeCommonly biphasic in lead V1 Best seen in leads II

Right Atrial Enlargement-Tall (> 2.5 mm), pointed P waves (P Pulmonale)

Left Atrial EnlargementNotched/bifid (M shaped) P wave (P mitrale) in limb leads

CONTDP Pulmonale

P Mitrale

Short PR IntervalWPW (Wolff-Parkinson-White) SyndromeAccessory pathway (Bundle of Kent) allows early activation of the ventricle (delta wave and short PR interval)

Long PR IntervalFirst degree Heart Block

QRS ComplexesNonpathological Q waves may present in I, III, aVL, V5, and V6

R wave in lead V6 is smaller than V5

Depth of the S wave, should not exceed 30 mm

Pathological Q wave > 2mm deep and > 1mm wide or > 25% amplitude of the subsequent R wave

QRS in LVH & RVH

Left Ventricular HypertrophySokolow & Lyon Criteria S in V1+ R in V5 or V6 > 35 mm An R wave of 11 to 13 mm (1.1 to 1.3 mV) or more in lead aVL is another sign of LVH

ST SegmentST Segment is flat (isoelectric)Elevation or depression of ST segment by 1 mm or moreJ (Junction) point is the point between QRS and ST segment

Variable Shapes Of ST Segment Elevations in AMI

T waveNormal T wave is asymmetrical, first half having a gradual slope than the second

Should be at least 1/8 but less than 2/3 of the amplitude of the R

T wave amplitude rarely exceeds 10 mm

Abnormal T waves are symmetrical, tall, peaked, biphasic or inverted.

T wave follows the direction of the QRS deflection.

T wave

QT intervalTotal duration of Depolarization and RepolarizationQT interval decreases when heart rate increasesFor HR = 70 bpm, QT13mm.Tallest R wave + deepest >35mm .R wave or S wave > 25mm .

Chamber Enlargment 3. RA: tall peaked P wave in limb leads. 4. RV: tall R waves in V1 , V2 .